Within the motor vehicle body, the B-pillar, which can also be referred to as central pillar or column, represents one of the most sophisticated parts because of the factors of its weight, stiffness and resonant frequency. The B-pillar is usually produced from two or more panel components and comprises at least one inner panel which, in the built-in condition in the motor vehicle body, faces a vehicle interior, as well as an outer panel which, accordingly, faces away from the vehicle interior. The outer panel, which can also be referred to as the outer shell, outer part, the outside of the B-pillar, or outer B-pillar, can be provided in the form of a U-shaped steel element which is closed from the vehicle interior by the inner panel. The inner panel can also be referred to as the cover, closing plate, inner plate or inside B-pillar. For the purpose of connecting the panels to one another, they can comprise lateral joining and connecting flanges which can be connected to one another by spot welding. The B-pillar integrated into the motor vehicle body can then, by further joining processes, be connected to the outer skin of the motor vehicle body, to the roof, or to glass surfaces.
From DE 10 2014 116 118 A1 there is known an outer part of a B-pillar which comprises an outer side panel, an upper panel, a lower panel and an inner side panel. The inner side panel, the upper panel and the outer side panel of the outer part of the B-pillar are joined together along lateral connecting flanges. The upper panel is connected to the lower panel along a region of overlap.
Due to the lateral joining and connecting flanges, the amount of material of the outer panel and inner panel is double-layered in these connecting regions. By connecting the two panels by spot welding which—along the joining and connecting flanges—normally only takes place every 30 to 50 mm—the outer panel and the inner panel are only partially connected to one another. In addition, because during spot welding heat is introduced into the material of the panels point-wise, there occur partial soft zones in the flanges which, if crash energy is introduced, are inclined to initiate a crack which, finally, can lead to crack failure in the B-pillar.
Furthermore, it is common practice to produce especially the outer panel from a Tailor Rolled Blank or a Tailor Welded Blank for the purpose of varying the plate thickness in the longitudinal direction of the outer panel. As a result, it is possible to provide reinforced regions, weaker regions and softer regions for specifically influencing the crash behaviour of the vehicle pillar in order to adapt the B-pillar to application-specific or market-specific requirements. However, at least in the region of spot-welded joined and connected flanges, said thickness variation has to be transferred to the inner panel. This also means that it is necessary to provide inner panels which correspond to the different outer panels. This leads to high costs and complicated logistics.
For reducing the weight of the B-pillar, it is known to produce the panels with thinner walls or out of light metal, and to increase their stiffness consistently or locally with fibre-reinforced plastic.
EP 1 867 559 A2 proposes a B-pillar which comprises a multi-panel structure with an outer panel and an inner panel welded thereto. For reinforcing the B-pillar it comprises an impact-resistant reinforcement part made of fibre-reinforced plastic which is glued to an inside of the inner plate.
From DE 2013017 269 A1 there is known a further B-pillar in a multi-panel design, wherein, for weight reducing purposes, there is produced an inner panel and an outer panel being connected to the inner panel; both panels are made of aluminium plates. To reinforce the B-pillar, reinforcing elements are arranged between the inner panel and the outer panel. A first one of the reinforcing elements is a plate metal part made of an aluminium alloy. A second one of the reinforcing elements is produced from fibre-reinforced plastics which is received between the first reinforcing element and the inner panel.
Further hybrid body components are known from DE 10 2012 203 888 A1 and DE 10 2011 111 232 A1. In order to reinforce heavily stressed body parts, it is known to reinforce plate metal components in the heavily stressed regions additionally with fibre-reinforced plastic components.
Due to the use of multi-panel designs comprising further reinforcing panels in addition to the outer panel and inner panel and due to the locally applied fibre-reinforced plastic reinforcing elements, such B-pillars are very expensive to produce. Furthermore, additional reinforcements are against the principle of lightweight construction.